May be that's the answer: we domesticated ourselves with school, police and other institutions and therefore we no longer need all our intelligence to survive

May be that's the answer: we domesticated ourselves with school, police and other institutions and therefore we no longer need all our intelligence to survive. We evolved to be the master hunters and nowadays our children aren't even aware meat comes from animals. This same limited amount of intelligence we evolved with, is then free to do something else, like literature, art and music.